[FS#436] asterisk13: Build fails with SRTP (lede)

[LEDE Bugs]

The following task is now closed:

FS#436 - asterisk13: Build fails with SRTP (lede)
User who did this - Mathias Kresin (mkresin)

Reason for closing: Invalid report
Additional comments about closing: The issue needs to be fixed in the telephony feed repository.

Please don't use the LEDE bugtracker for reporting bugs in external packages.

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=436